The present invention relates to a fused solid electrolytic capacitor, and particularly to a fusing arrangement thereof.
Solid electrolytic capacitors are used generally in various electronic circuits, and a fault rate thereof is small. The fault thereof, if it should occur, is often in a mode of short circuit, and when a large short-circuit current flows, a capacitor element is heated and sometimes caused to burn. For protecting circuit components from this excessive short-circuit current, a fuse is sometimes incorporated into a solid electrolytic capacitor. As for prior art, there is such a solid electrolytic capacitor with a fuse incorporated therein as disclosed in U.S. Pat. No. 4,224,656 issued on Sept. 23, 1980.
The fusing arrangement in this prior art has a fundamental structure wherein a cavity to house a fuse element therein is formed in an insulating body having copper laminated surfaces and both ends of the fuse element placed in the cavity is connected to the copper laminates on both sides. A lead is soldered to the copper laminate on one side at its one end and is connected to the cathode layer of a capacitor body at its other end. Another lead is soldered to the other side and lead out externally as an external lead. The fuse element is hermetically sealed in the cavity by the two leads soldered so as to close the openings of the cavity.
The structure of such a fusing arrangement as described above causes a manufacturing trouble of passing the fuse element through the cavity, thus obstructing mass-productivity.
Moreover, on the occasion when the two leads are soldered to the copper laminates to cover the openings of the cavity, solder happens to fill the cavity, causing a failure of spoiling the fusing effect.
Furthermore, slackening or distortion of a fuse element, if any, varies the effective length thereof, which cause a failure of nonuniformity in the fusing current characteristics of the fuse element.